A tunnel magnetic resistance element (TMR) includes a fixed magnetic layer in which a direction of magnetization is fixed, a free magnetic layer in which a direction of magnetization changes by receiving influence of a magnetic field from outside, and an insulating layer positioned between the fixed magnetic layer and the free magnetic layer, and this forms a magnetic tunnel junction (MTJ). The resistance of the insulating layer is changed by the tunnel effect according to a difference in the angle between the direction of the magnetization of the fixed magnetic layer and the direction of magnetization of the free magnetic layer.
In the free magnetic layer, a soft magnetic layer (NiFe, CoFeSiB, etc.) which easily reacts to the magnetic field from outside is positioned and a magnetic bonding layer is placed between a ferromagnetic layer joined to the insulating layer and the soft magnetic layer. With this, the bonding of the solid state properties between the magnetic tunnel junction and the soft magnetic material can be eliminated while using the synthetic bonding which generates only the magnetic bonding. With this, the resistance of the insulating layer can be changed linked to the change of the magnetic properties of the soft magnetic material which easily reacts to the magnetic field from outside, and high sensitivity can be obtained.
For example, the free magnetic layer in patent document 1 includes a ferromagnetic layer including CoFeB joined to an insulating layer, a soft magnetic layer including NiFe and a magnetic bonding layer including Ru in between the above.
Conventionally, the thinner the thickness of the magnetic bonding layer is, the synthetic bonding between the magnetic tunnel junction and the soft magnetic material becomes stronger and more stable, and the magnetic movement becomes stable. Therefore, the magnetic bonding layer is set to be very thin at about 0.5 nm (0.85 nm in the embodiment of cited document 1).